Applications (e.g., video games, maintenance simulators) operating on head mounted displays (HMDs) or personal viewing devices can include motion sensing to determine orientation of a character, a person or object within an environment. Different approaches for motion sensing exist. One approach is active tracking (e.g., inertial tracking), which involves placing a powered sensor (or sensors) on the object to be tracked and then processing the sensor readings either in or near the sensor.
Another possible approach is optical tracking, in which cameras are placed in the surrounding environment and targets are placed on the objects (e.g., head/arms/simulated weapon) to be tracked. In some embodiments, these cameras can emit a light from a light source (e.g., a coded light) to assist with the identification and location of the targets. The information received from the cameras is then extracted.
Disadvantages exist when implementing the approaches discussed above. For example, cameras being placed in the area surrounding the person or object being tracked can introduce latency into the system due to lead time associated with the start of actual tracking and also limits the size and place in which tracking can occur. The above approaches can track objects only when they are in a particular location (e.g., a person's hands cannot be tracked when the person is behind an obstruction (e.g., a sofa in a living room). The above-described approaches also often do not work in an outdoor environment with bright sunlight. The above approaches also often require installation and sometimes calibration of external sensors in fixed and known points in an environment. The above-described approaches also do not track movement from the view point of the user's head and eyes. In virtual reality and augmented reality applications, the position of the object/weapon/hand relative to the eyes/head can be more relevant to the displayed image environment than an absolute position relative to some fixed reference point.
Accordingly, a need exists for methods, systems and apparatus than can accomplish motion tracking from the point of view of a user's head and eyes and that facilitate the user's interaction with an environment (virtual or augmented) presented to the user. Another need also exits for virtual and augmented reality related methods, systems and apparatus applications that facilitate a 360 degree (e.g. fully spherical) tracking area as well as a limitless tracking area. Another need also exists for virtual and augmented reality related methods, systems and apparatus applications that can track both the orientation and position of an object or person.